Quadratic Functions

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Algebra II › Quadratic Functions

Questions 1 - 10

Based on the figure below, which line depicts a quadratic function?

Red line

Blue line

Green line

Purple line

None of them

Explanation

A parabola is one example of a quadratic function, regardless of whether it points upwards or downwards.

The red line represents a quadratic function and will have a formula similar to $\small {f(x)=ax^2+bx+c}$ .

The blue line represents a linear function and will have a formula similar to $\small {f(x)=ax+b$ .

The green line represents an exponential function and will have a formula similar to $\small {f(x)=ax^b}$ .

The purple line represents an absolute value function and will have a formula similar to $\small {f(x)=\left |ax+b \right |}.$ .

Consider the equation:

$y = 3x^{2} - 10x +5$

The vertex of this parabolic function would be located at:

$(\frac{5}{3}, \frac{-10}{3})$

$(\frac{-5}{3}, \frac{-10}{3})$

$(\frac{-5}{3}, 30)$

$(\frac{5}{3}, \frac{2}{25})$

$(\frac{5}{3}, \frac{27}{25})$

Explanation

For any parabola, the general equation is

$y = ax^{2} + bx +c$ , and the x-coordinate of its vertex is given by

$x = \frac{-b}{2a}$ .

For the given problem, the x-coordinate is

$x = \frac{-(-10)}{2(3)} = \frac{5}{3}$ .

To find the y-coordinate, plug $\frac{5}{3}$ into the original equation:

$y = 3(\frac{5}{3})^{2} - 10(\frac{5}{3}) +5 = \frac{-10}{3}$

Therefore the vertex is at $(\frac{5}{3}, \frac{-10}{3})$ .

$(x-1)^2+(y-1)^2\geq25$

Given the above circle inequality, which point is not on the edge of the circle?

Explanation

This is a graph of a circle with radius of 5 and a center of (1,1). The center of the circle is not on the edge of the circle, so that is the correct answer. All other points are exactly 5 units away from the circle's center, making them a part of the circle.

Which of the following inequalities is not hyperbolic?

$[(x+4)^2]/9 + [(y-2)^2]/100 \leq 1$

$[(y-4)^2]/49 - [(x-1)^2]/4 \geq 7$

Explanation

The equation for a horizontal hyperbola is. The equation for a vertical hyperbola is . Hyperbolic inequalities use an inequality sign rather than an equals sign, but otherwise have the same form as hyperbolic equations. The fact that the right side of the inequality is not equal to 1 does not change the fact that , and $[(y-4)^2]/49 - [(x-1)^2]/4 \geq 7$ represent hyperbolas, since THESE can all be simplified to create an inequality with 1 on the right side (by dividing both sides of the equation by the constant on the right side of the inequality.) Answer choice $[(x+4)^2]/9 + [(y-2)^2]/100 \leq 1$ is the only option in which the two terms on the left side of the inequality are combined using addition rather than subtraction, creating an ellipse rather than a hyperbola. (The equation for an ellipse is .)

Based on the figure below, which line depicts a quadratic function?

Red line

Blue line

Green line

Purple line

None of them

Explanation

A parabola is one example of a quadratic function, regardless of whether it points upwards or downwards.

The red line represents a quadratic function and will have a formula similar to $\small {f(x)=ax^2+bx+c}$ .

The blue line represents a linear function and will have a formula similar to $\small {f(x)=ax+b$ .

The green line represents an exponential function and will have a formula similar to $\small {f(x)=ax^b}$ .

The purple line represents an absolute value function and will have a formula similar to $\small {f(x)=\left |ax+b \right |}.$ .

What is the center and radius of the following equation, respectively?

$(6,-7); \sqrt2$

$(-6,7); \sqrt2$

Explanation

The equation given represents a circle.

represents the center, and is the radius.

The center is at:

Set up an equation to solve the radius.

The radius is: $r=\sqrt{2}$

The answer is: $(6,-7); \sqrt2$

Consider the following two functions:

$f(x) = x^{2}$ and $g(x) = (x+3)^{2} - 6$

How is the function shifted compared with ?

units left, units down

units right, units down

units left, units up

units right, units down

units left, units down

Explanation

The $(x+3)^{2}$ portion results in the graph being shifted 3 units to the left, while the results in the graph being shifted six units down. Vertical shifts are the same sign as the number outside the parentheses, while horizontal shifts are the OPPOSITE direction as the sign inside the parentheses, associated with .